BAGHDAD — Iraq's prime minister called on Sunni tribal fighters to abandon the Islamic State group Sunday, ahead of a promised offensive to retake Saddam Hussein's hometown from the extremists.

Haider al-Abadi offered no timeline for an attack on Tikrit, the hometown of the late Iraqi dictator some 130 kilometers (80 miles) north of Baghdad that fell into the hands of the Islamic State group last summer. However, Shiite militias and Iraqi security forces have stationed themselves around Tikrit as state-run media has warned that the city "will soon return to its people."

But sending Shiite militias into the Sunni city of Tikrit, the capital of Iraq's Salahuddin province, could reprise the bloody, street-by-street insurgent battles that followed the 2003 U.S.-led invasion of Iraq. On Saturday, two suicide car bombers killed 16 nearby Shiite militiamen and wounded 31.

Al-Abadi offered what he called "the last chance" for Sunni tribal fighters, promising them a pardon during a news conference in Samarra, 95 kilometers (60 miles) north of Baghdad. His office said he arrived in Samarra to "supervise the operation to liberate Tikrit from the terrorist gangs."

"I call upon those who have been misled or committed a mistake to lay down arms and join their people and security forces in order to liberate their cities," al-Abadi said.

Al-Abadi said the operation will see troops come from several directions, but he declined to give an exact time for the operation's start. However, his presence in Samarra suggests it could come soon. A statement from his office late Sunday announced the start of a security operation to "liberate" Salahuddin province, though there were no initial reports of any military action underway.

The Iraqi military previously launched an operation in late June to try to wrest back control of Tikrit, but that quickly stalled after making little headway. Other planned offensives by Iraq's military, which collapsed under the initial Islamic State group blitz, also have failed to make up ground, though soldiers have taken back the nearby refinery town of Beiji, backed by airstrikes from a U.S.-led coalition.

Tikrit, which occasionally saw attacks on U.S. forces during the American occupation of the country, is one of the biggest cities held by the Islamic State group. It also sits on the road to Mosul, Iraq's second-largest city, which is also held by the extremists. Any operation to take Mosul likely would require Iraq to seize Tikrit first.

Al-Abadi's comments appear to be targeting former members of Iraq's outlawed Baath party, loyalists to Saddam Hussein, who joined the Islamic State group during its offensive, as well as other Sunnis who were dissatisfied with Baghdad's Shiite-led government. The premier likely hopes to peel away some support from the Islamic State group, especially as Iraqis grow increasingly horrified by the extremists' mass killings and other atrocities.

In February alone, violence across Iraq killed at least 1,100 Iraqis, including more than 600 civilians, the U.N. Assistance Mission in Iraq said Sunday.

"Daily terrorist attacks perpetrated by ISIL continue to deliberately target all Iraqis," Mladenov said, using an alternate acronym for the Islamic State group. "There are also concerning reports of a number of revenge killings by armed groups in areas recently liberated from ISIL."

Last year was the deadliest in Iraq since its 2006-2007 sectarian bloodshed, with a total of 12,282 people killed and 23,126 wounded, according to the U.N.